// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_GFX_ANIMATION_ANIMATION_CONTAINER_H_
#define UI_GFX_ANIMATION_ANIMATION_CONTAINER_H_

#include <set>

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "ui/gfx/gfx_export.h"

namespace gfx {

class AnimationContainerElement;
class AnimationContainerObserver;

// AnimationContainer is used by Animation to manage the underlying timer.
// Internally each Animation creates a single AnimationContainer. You can
// group a set of Animations into the same AnimationContainer by way of
// Animation::SetContainer. Grouping a set of Animations into the same
// AnimationContainer ensures they all update and start at the same time.
//
// AnimationContainer is ref counted. Each Animation contained within the
// AnimationContainer own it.
class GFX_EXPORT AnimationContainer
    : public base::RefCounted<AnimationContainer> {
public:
    AnimationContainer();

    // Invoked by Animation when it needs to start. Starts the timer if necessary.
    // NOTE: This is invoked by Animation for you, you shouldn't invoke this
    // directly.
    void Start(AnimationContainerElement* animation);

    // Invoked by Animation when it needs to stop. If there are no more animations
    // running the timer stops.
    // NOTE: This is invoked by Animation for you, you shouldn't invoke this
    // directly.
    void Stop(AnimationContainerElement* animation);

    void set_observer(AnimationContainerObserver* observer)
    {
        observer_ = observer;
    }

    // The time the last animation ran at.
    base::TimeTicks last_tick_time() const { return last_tick_time_; }

    // Are there any timers running?
    bool is_running() const { return !elements_.empty(); }

private:
    friend class base::RefCounted<AnimationContainer>;

    typedef std::set<AnimationContainerElement*> Elements;

    ~AnimationContainer();

    // Timer callback method.
    void Run();

    // Sets min_timer_interval_ and restarts the timer.
    void SetMinTimerInterval(base::TimeDelta delta);

    // Returns the min timer interval of all the timers.
    base::TimeDelta GetMinInterval();

    // Represents one of two possible values:
    // . If only a single animation has been started and the timer hasn't yet
    //   fired this is the time the animation was added.
    // . The time the last animation ran at (::Run was invoked).
    base::TimeTicks last_tick_time_;

    // Set of elements (animations) being managed.
    Elements elements_;

    // Minimum interval the timers run at.
    base::TimeDelta min_timer_interval_;

    base::RepeatingTimer timer_;

    AnimationContainerObserver* observer_;

    DISALLOW_COPY_AND_ASSIGN(AnimationContainer);
};

} // namespace gfx

#endif // UI_GFX_ANIMATION_ANIMATION_CONTAINER_H_
